The metering information is crucial information for the distribution of fluids, notably in the context of a network comprising a large number of stations delivering these fluids.
Thus, when the fluid is a gas, the volume of gas consumed by each client, which is available directly on each meter, can be repeated in the form of a succession of electrical pulses. The device that generates this repetition is called a “low frequency transmitter” or “low frequency outlet” (LF outlet). The LF outlet is located on the casing of the meter, and thus is easily accessible to any agent or technician of the gas distributor. The succession of pulses can be recorded and used by different types of apparatuses, such as, for example, a remote meter reading device and an energy monitoring device.
During technical interventions on the delivery stations, the agents or technicians of the distributor of the fluid must be able to identify the wiring system of the LF outlets of the gas meters. Although efforts have been undertaken to standardize the wiring system of these outlets, daily experience has shown that the fleet of apparatuses is not uniform as far as the wiring system of the LF outlets is concerned. According to recent statistics, approximately 40% of the failures of remote meter reading of consumption data are due to a non-standardized wiring system of the LF outlets.
The low frequency transmitter is in the form of a connector with several pins, often six pins, which explains its second name, “outlet.” In general, two pins represent a metering switch, and two different pins represent an anti-fraud switch.
However, it is also conceivable in some cases for one LF outlet to have two metering wiring systems and an anti-fraud wiring system. Example: metering switches on pins 1-2; 3-5, and anti-fraud switch on pins 4-6 of a six-pin outlet.
The LF outlet has the special feature of containing flexible blades in the switches (FBS) that commute from one state to the other due to the presence of a magnet in front of the connector. As a result, the connector can be configured depending on the two cases:
absence of the magnet: connector configured in the rest state, and
presence of the magnet: connector configured in the active state.
The following are the resulting configurations for the LF outlet:
The outlet is in the rest state: (configuration No. 1)
In this case, the anti-fraud switch is normally closed (NC) and the metering switch is normally open (NO). In the diagram represented in FIG. 1, the anti-fraud switch is located between the pins 1 and 3 of the connector, and the metering switch between the pins 4 and 5.
The outlet changes to the active state: (configuration No. 2)
The presence of a magnet in front of the connector results in the commutation of the flexible blade switches (FBS) present within the LF outlet. The initially closed (NC) anti-fraud switch is opened (O), and the initially open (NO) metering switch is closed (C). The outlet thus changes to the active state (see FIG. 2).
The installation of remote meter reading and remote reporting systems, or any other system using the pulses available to the LF outlet, is generally fairly simple. However, the wiring system may be complicated because of its diversity (no wiring system standard defined by the manufacturers of meters) and the absence of diagrams at the delivery stations. The agent or technician is thus obligated to manually test each of the pins of the LF outlet of a meter.
This detection or identification of the pins occurs in two steps:
The first step consists in detecting or identifying the anti-fraud pins. This detection is carried out without any intervention on the meter, the latter being in the rest state (the opposite state of the metering state): the anti-fraud pins are connected, and the metering pins are disconnected.
The second step consists in detecting or identifying the metering pins. This detection is carried out after the placement of a magnet in front of the LF pin: the anti-fraud pins are disconnected, and the metering pins are connected.
This identification represents a great loss of time for the agent or technician, since he/she must use a multimeter and a magnet for testing the connection between two different pins, for all the different possible combination of pins.